Booms are commonly employed in lifting and transporting a load. When utilized for this purpose, the booms are provided with an end bearing capable of providing for rotation of the boom in two axes and of absorbing the vertical and horizontal loads imposed. In shipboard applications, such bearings are known as gooseneck bearings. On a tuna fishing vessel, a main boom is utilized for net handling. Additionally, a cargo and brailing boom is utilized to brail fish from the nets and to unload cargo aboard the vessel. The booms in all such vessel applications are located above deck and thereby subject the associated bearing to the severe marine environment. According to conventional practice, the various bearing surfaces in gooseneck bearings are provided with grease fittings and packed with grease in an attempt to exclude salt and other contaminates. However, the demands of daily use, in conjunction with the penetration of contaminants, frequently destroy the effectiveness of the lubrication and causes metal to metal contact between the bearing surfaces. The high loads that may be carried by such booms in combination with the reduced lubrication effectiveness may ultimately cause bearing failure. A load carried on the boom acts through a relatively long lever arm and produces sufficient moment to cause failure of the main bearing structural components, such as the boom swivel pin, or boom heel pin. Such failure is a potential safety hazard, in addition to being an expensive interruption of critical vessel tasks.
It is therefore an object of the invention to provide a new and improved apparatus for supporting the end of a load carrying boom in a bearing structure that is sealed against the admission of deleterious elements